1. Field of the Invention
This invention in general relates to an apparatus for coupling multiple sources of radiation into a waveguide device, such as an optical fiber or fiber laser, and, in particular, to a system using a unitary deflecting component to provide coupling, particularly with discrete sources of laser radiation.
2. Description of the Prior Art
There continues to be a need for ever-increasing levels of radiative power in applications such as printing, fabrication, and medical treatment. A commonly-used approach is to optically couple the emission beams from multiple radiative sources into an optical fiber or a fiber laser such that output radiation having a higher power level is emitted from the waveguide. The relevant art disclosed various configurations of such optical coupling systems. U.S. Pat. No. 5,418,880 issued to Lewis et al., for example, discloses a high-power fiber device powered by a linear array of laser diodes. The optical coupling system comprises an optical beam rotator for transforming the output of the laser diode array and transmitting the transformed output to collimating optics from which the radiation is coupling into the waveguide. In another approach, U.S. Pat. No. 5,333,077 issued to Legar et al. discloses a lens system comprising a first optical element for receiving and redirecting a laser beam from a linear diode array, for example, and a second optical element for further redirecting the laser beam to a focal point.
When greater levels of emitted power are required, discrete sources of radiation, such as laser diode devices, may be used. However, because of larger physical sizes and greater cooling requirements of these discrete devices, they cannot be emplaced in close proximity to one another and, consequently, cannot be adapted to be used in conjunction with the coupling devices designed for linear diode arrays. Rather, a plurality of separate mirrors is typically used to redirect the multiple radiation beams from discrete devices into the optical waveguide. For example, U.S. Pat. No. 4,828,357 issued to Arata et al. discloses an apparatus producing a high-power laser beam comprising a plurality of directing mirrors, a plurality of reflecting mirrors, and a central focusing mirror for focusing the resultant laser beam into one focal point. Another approach is disclosed in U.S. Pat. No. 5,210,643 issued to Fujii et al. in which an improved efficiency of combining laser beams is achieved through the use of suitably positioned dichroic mirrors and a beam splitter.
Unfortunately, the use of an arrangement of separate mirrors results in a system sensitive to misalignment and inadvertent movement, which results in complexity of alignment. Moreover, the use of multiple, separate mirrors makes it difficult to maintain the relative alignment of linearly-polarized beams at the waveguide input facet without the use of additional optical elements.
While the prior art describes a variety of optical coupling devices, there does not appear to have been disclosed in the relevant art a unitary device for coupling multiple sources of radiation into a waveguide, and it is a primary object of this invention to provide such a device.
It is another object of the present invention to provide such a device which can be used with discrete sources of laser radiation.
It is a further object of the present invention to provide such a device with which beams can be combined while maintaining relative alignment of the beam directions of polarization.
Other objects of the invention will be obvious, in part, and, in part, will become apparent when reading the detailed description to follow.